Experimental Identification of Ultrafast Reverse Hole Transfer at the Interface of the Photoexcited Methanol/Graphitic Carbon Nitride System

Abstract

An experimental scrutiny of the photoexcited hole dynamics in a prototypical system is presented in which hole-scavenging methanol molecules are chemisorbed on a graphitic carbon nitride (g-C N ) substrate. A set of comparison and control experiments by means of femtosecond time-resolved transient absorption (fs-TA) spectroscopy were conducted. The elusive reverse hole transfer (RHT) process was identified, which occurs on a timescale of a few hundred picoseconds. The critical role of interfacially chemisorbed methoxy (instead of methanol) as the dominant species responsible for hole scavenging was confirmed by a control experiment using protonated g-C N as the substrate. A hot-hole transfer effect was revealed by implementing different interband photoexcitation scenarios. The RHT rate is the key factor governing the hole-scavenging ability of different hole scavengers.

MOFs Conferred with Transient Metal Centers for Enhanced Photocatalytic Activity

“…Neutral singlet excitons, which manifest as a probe bleach of neutral groundstate absorption, result in the broad and negative profiles in the range of about 420-700 nm, while the photoinduced absorption of electrons in the Cu-NM causes the broad and positive profiles. [26] No positive TA signal (Figure 4 a) in NM was detected in the range of 420-700 nm (1.1-2010.3 ps) because of the fast charge electron-hole recombination, whereas Cu-NM possesses strong positive TA signals (Figure 4 b). No obvious decay was observed for these positive signals, indicating a continuous transfer of electrons from the organic linkers to the Cu species.…”

Ab initio nonadiabatic molecular dynamics investigations on the excited carriers in condensed matter systems

“…It was also proved that the CH 3 O is the dominate species for hole trapping. 84 The timescales for the forward and reverse hole transfer obtained in the experiments are at ps magnitude, which are much longer than the theoretical results for CH 3 OH/TiO 2 . This might be due to the complicated environment in the experiments which is not included in the simulation.…”

“…Recently, both the forward and reverse hole transfer were measured in CH 3 OH/C 3 N 4 system. It was also proved that the CH 3 O is the dominate species for hole trapping . The timescales for the forward and reverse hole transfer obtained in the experiments are at ps magnitude, which are much longer than the theoretical results for CH 3 OH/TiO 2 .…”

Potassium‐Ion‐Assisted Regeneration of Active Cyano Groups in Carbon Nitride Nanoribbons: Visible‐Light‐Driven Photocatalytic Nitrogen Reduction

“…As shown in Figure S6, no measurable NH 3 is yielded from the control experiments without a photocatalyst but with irradiation, and with a photocatalyst but without irradiation. The photocatalytic NRR experiments were carried out using an alcoholic ethylene glycol (EG) as the reaction medium because EG possesses high N 2 solubility and is rich in α‐hydrogen atoms that can act as proton donors . Figure c shows the yielded NH 3 under photocatalysis conditions when g‐C 3 N 4 and m CNN are employed as the photocatalysts.…”